CN105547460A - Double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with weak reflection grating, and method for double-pulse phase sensitive OTDR - Google Patents
Double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with weak reflection grating, and method for double-pulse phase sensitive OTDR Download PDFInfo
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Abstract
The invention discloses a double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with a weak reflection grating, and the OTDR comprises a narrow-pulse laser, a light modulator, a circulator, a data collection device, an avalanche detector, a weak reflection grating array, a sensing optical fiber, and a pulse signal generator. The invention also discloses a vibration measurement method for the OTDR. The OTDR employs a mode of integrating with the weak reflection grating, and improves the signal to noise ratio of a system. Through employing a double-pulse detection method, the OTDR solves a problem that most of grating sensing is just sensitive to the position event of a grating, and is enabled to be sensitive to all events of the sensing fiber along a line. Because the signal to noise ratio of the system is very high, the OTDR can measure the high-frequency vibration of limit frequency under the limiting of the length of the sensing fiber, and also can measure the low-frequency vibration (less than 10 hertz).
Description
Technical field
The present invention relates to sensory field of optic fibre, particularly merge dipulse phase sensitive optical time domain reflectometer and the method thereof of weak reflection grating.
Background technology
Phase sensitive optical time domain reflection technology (Φ-OTDR) realizes the detection of disturbance to external world by the change of the interference signal detecting back rayleigh scattering light in sensor fibre, and it has the advantage of high sensitivity, distributed measurement, distance sensing length.Φ-OTDR is by H.F.Taylor (TaylorHF the earliest, in 1993 year propose LeeCE.Apparatusandmethodforfiberopticintrusionsensing [P] .1993-.http: //www.google.co.uk/patents/US5194847), its basic structure is similar to OTDR, unique not being both have employed narrow linewidth laser as light source, the scattered light of each scattering center superposed is interfered mutually, forms the backscattering light curve of shake.External disturbance can affect the direct phase differential of each scattered light of superposition, thus causes the scattered light curve of outgoing to change, and detects this change and can realize the monitoring of optical fiber along line states.But, the amplitude of back rayleigh scattering light is general all very little, for the incident pulse of 1us, about little-the 53dB of power ratio incident optical power of its back rayleigh scattering light, so need to adopt the method for high sensitivity photodetector, coherent detection or average data processing method etc. in traditional Φ-OTDR, these methods can be brought the complexity of increase system, reduce some shortcomings such as detectable vibration frequency range.
Weak reflection grating (UWFBG) is an emerging technology.A series of weak reflection grating with same centre wavelength and reflectivity is spaced on sensor fibre according to fixing, forms weak reflection grating array.When detecting optical pulses is through weak reflection grating, very little a part of luminous power is reflected by weak reflection grating array, forms high power reflected impulse clearly, and remaining light also can continue to realize long propagation in sensor fibre simultaneously.Quasi-distributed optical fiber sensing (the X.Li of the scholars such as X.Li, X.Wang by adopting weak reflection grating to achieve High Extinction Ratio, Q.Sun, D.Liu, R.Liang, J.Zhang, J.Wo, P.P.Shum, andD.Liu, " Simultaneouswavelengthandfrequencyencodedmicrostructureb asedquasi-distributedtemperaturesensor; " Opt.Express20,12076-12084 (2012); X.Wang, Z.Yan, F.Wang, ChengboMou, Z.Sun, X.Zhang, andL.Zhang, " SNRenhanceddistributedvibrationfibersensingsystememployi ngpolarization-OTDRandultra-weakFBGs, " IEEEPhotonicsJournal7,680051 (2015) .).Although adopt weak reflection grating array can solve the very little problem of back rayleigh scattering luminous power to a certain extent, but adopt in the method for sensing of weak reflection grating array at present, system is mostly only sensitive to the event occurring in and be furnished with weak reflection grating place, and what this reduced sensor-based system greatly spatially can sensing scope.
Summary of the invention
Technical matters to be solved by this invention overcomes the deficiencies in the prior art and provides the dipulse phase sensitive optical time domain reflectometer and method thereof that merge weak reflection grating, the present invention proposes while the weak reflection grating of employing obtains high s/n ratio, adopt dipulse detection light signal, make the event of system sensitive any point on sensor fibre, and realize high-frequency vibration survey.
The present invention is for solving the problems of the technologies described above by the following technical solutions:
According to a kind of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating of the present invention, comprise narrow linewidth laser, photomodulator, circulator, data collector, avalanche probe, sensor fibre, pulse signal generator and be arranged on the weak reflection grating array on sensor fibre; Wherein,
Narrow linewidth laser, for exporting continuous light to photomodulator;
Pulse signal generator, for controlling the data acquisition of photomodulator and synchronous data collection device;
Photomodulator, for being modulated into first port of detection pulse-pair output to circulator according to the control of pulse signal generator by continuous light;
Circulator, injects sensor fibre for detecting dipulse by its second port, obtains the second port that the back rayleigh scattering light signal comprising a series of interference pulse inputs to circulator, and export avalanche probe to by the 3rd port of circulator;
Avalanche probe, exports data collector to for converting the back rayleigh scattering light signal comprising a series of interference pulse to electric signal;
Data collector, for processing electric signal, obtains the disturbance information of sensor fibre.
As a kind of further prioritization scheme of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating of the present invention, described weak reflection grating array is engraved on sensor fibre, weak reflection grating array is made up of the weak reflection grating that N number of reflectivity is equal, reflectivity is-55dB ~-30dB, interval between adjacent weak reflection grating is equal
wherein, L is sensor fibre total length, and Δ L is the distance interval between adjacent weak reflection grating,
represent and round downwards.
As a kind of further prioritization scheme of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating of the present invention, described detection dipulse comprises two light pulses, is respectively prepulse and afterpulse; If the time interval of front and back pulse is τ,
the pulse width of prepulse and afterpulse is equal, pulse width
wherein, c is the light velocity in vacuum, n
ffor sensor fibre refractive index, Δ L is the distance interval between adjacent weak reflection grating.
As a kind of further prioritization scheme of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating of the present invention, described photomodulator can be electrooptic modulator or acousto-optic modulator.
Based on a kind of method merging the measuring vibrations of the dipulse phase sensitive optical time domain reflectometer of weak reflection grating, comprise the following steps:
Step one, continuous light is modulated into detection dipulse, launches according to predetermined period and detect dipulse for M time in sensor fibre;
Step 2, detection dipulse produce return signal dorsad in the sensor fibre being carved with weak reflection grating array, and return signal is the back rayleigh scattering light signal comprising a series of interference pulse dorsad; M detection obtains M bar return signal curve dorsad;
Step 3, by M bar dorsad return signal curve arrange in chronological order, obtain the time dependent curve of power that on sensor fibre, every bit is corresponding, and the powertrace corresponding to every bit on sensor fibre carries out Fourier transform, obtain spectrogram, thus realize the location of vibration and the large-range measuring to vibration frequency.
The present invention adopts above technical scheme compared with prior art, has following technique effect:
(1) the present invention adopts the optical fiber merging weak reflection grating array as sensor fibre, and the signal obtained has very high signal to noise ratio (S/N ratio); The present invention adopts dipulse as detection light signal, solves the problem that the sensor-based system merging fiber grating is mostly " point is responsive ", achieves the disturbance being sensitive to sensor fibre any point;
(2) the present invention is when realizing vibration survey, without the need to the data processing such as being averaged, can realize the vibration survey of ultra-high frequency, and high-quality signal can also realize the measurement of lower frequency (~ 3Hz) simultaneously;
(3) measuring system apparatus structure of the present invention is simple and cost is lower.
Accompanying drawing explanation
Fig. 1 is the schematic diagram that the high s/n ratio dipulse phase place optical time domain reflectometer of weak reflection grating is merged in the present invention.
Fig. 2 is the sensor fibre schematic diagram merging weak reflection grating array in phase place optical time domain reflectometer of the present invention.
Fig. 3 is that the detection dipulse schematic diagram comprised in the high s/n ratio dipulse phase place optical time domain reflectometer of weak reflection grating is merged in the present invention.
Fig. 4 is that the reflected impulse that in the present invention, front and back pulse produces in adjacent weak reflection grating interferes the schematic diagram producing interference pulse phenomenon; Wherein, (a) produces the process of the first reflected impulse for prepulse in weak reflection grating, and (b) is first, second reflected impulse superposed transmission.
Fig. 5 is the sensor fibre emergent light power diagram along the line measured by high s/n ratio dipulse phase place optical time domain reflectometer that weak reflection grating is merged in the present invention.
Fig. 6 is that the sensor fibre measured by high s/n ratio dipulse phase place optical time domain reflectometer of weak reflection grating spectrogram along the line is merged in the present invention; Wherein, a () is the spectrogram under 30Hz vibrational perturbation, b () is the partial enlarged drawing of optical fiber spectrogram along the line under 30Hz disturbance, c () is the spectrogram under 9kHz vibrational perturbation, (d) is the partial enlarged drawing of optical fiber spectrogram along the line under 9kHz disturbance.
Reference numeral is interpreted as: 1-narrow linewidth laser, 2-photomodulator, 3-circulator, 4-data collector, 5-avalanche probe, the weak reflection grating of 6-, 7-sensor fibre, 8-pulse signal generator, U1, U2, U3, U4, U5 are the weak reflection grating that sensor fibre arranges along the line, P1-prepulse, P2-afterpulse.
Embodiment
Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:
With reference to Fig. 1, the high s/n ratio dipulse phase place optical time domain reflectometer of the weak reflection grating of fusion of the present invention, comprises narrow linewidth laser 1, photomodulator 2, circulator 3, data collector 4, avalanche probe 5, weak reflection grating array, sensor fibre 7, pulse signal generator 8.Described narrow linewidth laser 1 sends continuous light and is modulated into detecting optical pulses through photomodulator 2, this detecting optical pulses comprises former and later two light pulses, as shown in Figure 3, be called detection dipulse, detection dipulse enters sensor fibre 7 by the A port of circulator 3, sensor fibre is covered with weak reflection grating array along the line, weak reflection grating array is engraved on sensor fibre, weak reflection grating array is made up of the weak reflection grating 6 that N number of reflectivity is equal, reflectivity is-55dB ~-30dB, interval between adjacent weak reflection grating is equal
wherein, L is sensor fibre total length, and Δ L is the distance interval between adjacent weak reflection grating,
represent and round downwards.Detection dipulse is transmitted in sensor fibre, is not having the region of weak reflection grating, Rayleigh scattering will occur; Reflection will be produced in weak reflection grating region, form reflected impulse, the reflected impulse that front and back pulse produces in adjacent weak reflection grating spatially will produce overlapping, interfere, produce interference pulse, return signal is the back rayleigh scattering light signal comprising a series of interference pulse dorsad, return signal is transmitted to the B port of circulator 3 dorsad, exported by the C port of circulator 3, converted to electric signal by avalanche probe 5 detection, electric signal is obtained by data collector 4, through the disturbance information of data processing determination current sensor optical fiber.Pulse signal generator 8 produces qualified detection dipulse for controlling photomodulator, and is used for the data acquisition of synchronous data collection device 4.
The sensor fibre of the weak reflection grating array of fusion of the present invention as shown in Figure 2, the long 4.5km of sensor fibre, to be intervally arranged several weak reflection gratings according to fixing distance along the line, the distance between adjacent weak reflection grating is spaced apart Δ L=50m, and grating number is N=88.
Of the present invention produced detection dipulse as shown in Figure 3, comprises two light pulses, is respectively prepulse P1 and afterpulse P2, and former and later two light pulse amplitudes are equal.The time interval of front and back pulse is τ=500ns, and the pulse width of front and back pulse is equal, pulse width t
p=300ns.
The return signal dorsad produced in the present invention is a back rayleigh scattering light curve comprising a series of interference pulse, wherein the power of interference pulse is far above back rayleigh scattering signal, interference pulse is the main detectable signal for detecting disturbance, there is high s/n ratio, be easy to detection and realize remote.To the defining method of each point in return signal be dorsad: in the t=0 moment from the utilizing emitted light pulse of optical fiber one end, from 0 moment, pulsed light emission end will receive a series of return signal, measure the time interval Δ t between return signal corresponding to any point and incident light pulse delivery time, according to formula z=ct/ (2n
f) determine between this point and pulsed light emission end distance z.
In the present invention, the reflected impulse that front and back pulse produces in adjacent weak reflection grating interferes the schematic diagram of generation interference pulse phenomenon as shown in Figure 4.Appoint and get continuous print three weak reflection gratings in weak reflection grating array, respectively UWFBG
1, UWFBG
2, UWFBG
3; Appoint and get a moment t
0, suppose that the prepulse now detecting dipulse is just in time through UWFBG
3, then prepulse is at UWFBG
3upper generation reflected impulse, as shown in dashed pulse in (a) in Fig. 4, is called the first reflected impulse; The time interval of front and back pulse is τ,
the pulse width of prepulse and afterpulse is equal, pulse width
wherein, c is the light velocity in vacuum, n
ffor sensor fibre refractive index, Δ L is the distance interval between adjacent weak reflection grating; Subsequent time t
0+ τ/2, afterpulse is just in time through UWFBG
2, afterpulse is also at UWFBG
2upper generation reflected impulse, and toward transmission back, as shown in chain line pulse in (b) in Fig. 4, be called the second reflected impulse; And now as shown in (b) in Fig. 4, the first reflected impulse also just in time transfers to herein, overlap in time with the second reflected impulse, form detectable signal together, toward transmission back.Because the laser instrument produced in the present invention is narrow linewidth laser, so two reflected impulses can interfere.
Suppose that the Jones vector of two reflected impulses interfered is respectively
Adopt Jones vector expression way to be consider that two reflected impulses interfered come from two different weak reflection gratings and light pulse, different power and polarization state may be had.In formula, δ φ represents the phase differential between two reflection light pulses, A
1be the electric field amplitude of the first reflected impulse, E
1be the electric field intensity of the first reflected impulse, p
1xrepresent the power proportions in the first reflected impulse x direction, φ
1represent the phase differential of two orthogonal modes of the first reflected impulse, A
2be the electric field amplitude of the second reflected impulse, E
2be the electric field intensity of the second reflected impulse, p
2xrepresent the power proportions in the second reflected impulse x direction, φ
2represent the phase differential of two orthogonal modes of the second reflected impulse, i is imaginary unit.
When first, second reflected impulse overlaps on together, when interfering, the interference pulse power of outgoing can be expressed as
Wherein, indicate
represent conjugation.When the expression formula of first, second pulse being substituted into, interference pulse power can be obtained such as formula shown in (3).
In formula,
λ is lambda1-wavelength, n
ffor sensor fibre refractive index, Δ L is the distance interval between adjacent weak reflection grating.
Fig. 5 is the sensor fibre emergent light power diagram along the line that the high s/n ratio dipulse phase place optical time domain reflectometer of the weak reflection grating of fusion of the present invention records.Sensor fibre length is about 4500m, optical fiber spreads all over about 88 weak reflection gratings, interval delta L=50m between each grating, incident detecting optical pulses width t
p=300ns, recurrent interval τ=500ns.In figure, horizontal ordinate represents the point that optical fiber is along the line, ordinate represents the back light power magnitude of each point, curve comprises 89 pulse signals, first is the reflected impulse formed on first weak reflection grating, afterpulse in the end a weak reflection grating by prepulse with last pulse signal respectively, insensitive to the vibration on sensor fibre; And middle 87 is the interference pulse formed that is concerned with by the reflected impulse of dipulse successively in adjacent weak reflection grating, be sensitive to the vibration that sensor fibre is along the line.The width of each interference pulse is 300ns in time domain, consistent with theory.The reflectivity of weak reflection grating is about-40dB, and now interference pulse is compared back rayleigh scattering signal and about exceeded 18dB, has higher signal to noise ratio (S/N ratio).
In the present invention, when sensor fibre occurring dynamic disturbances, consider that the length of weak reflection grating is shorter, so dynamic disturbances is generally considered to appear between two weak reflection gratings.Be subject to the impact of electrooptical effect, poisson effect and strain, the refractive index n of optical fiber
fto change with fiber lengths Δ L, so the phase differential δ φ of two reflected impulses will change, cause interference pulse power I to change.By detecting the change of Output optical power, the measurement to dynamic disturbances can be realized.Because native system has higher signal to noise ratio (S/N ratio), do not need to be averaged to return signal dorsad, thus native system to the high frequency response of vibration close to the highest frequency c/4nL determined by Nyquist's theorem; Simultaneously because low-frequency noise is very little, the measurement of lower frequency (~ 3Hz) also can be realized.
In measurement, enter sensor fibre according to fixing periodic emission M=2000 detection dipulse, obtain 2000 return signals dorsad.The sampling rate of data collector is 500MSa/s, and therefore corresponding between adjacent two sampled points fiber lengths is 0.203m.2000 curves are arranged in chronological order, obtains the time dependent curve of power that on optical fiber, every bit is corresponding.To the every bit on optical fiber, Fourier transform is carried out to its powertrace, obtain the spectrogram of every bit.The frequency spectrum in interference pulse region is be concerned about probe signal spectrum.Time not vibrated between two weak reflection gratings, the power approximately equal of each frequency on the spectrogram that the interference pulse that these two weak reflection gratings produce is corresponding; And when having optical fiber to be subject to vibrating between two weak reflection gratings, by spike larger for emergent power value on the spectrogram that the interference pulse that these two weak reflection gratings produce is corresponding, thus the location realized vibration, and the frequency that on power spectrum, spike is corresponding is vibration frequency, thus achieve the measurement to vibration frequency.As can be seen from above elaboration also, the vibration that the high s/n ratio dipulse phase place optical time domain reflectometer that weak reflection grating is merged in the present invention occurs optical fiber optional position is all responsive, and vibration can be navigated between two gratings being adjacent, therefore positioning precision equals grating spacings.
The quality of detectable signal can represent with visibility V,
in a system of the invention, interference pulse power is main detectable signal.And the extreme value of interference pulse is determined by the phase differential between two reflected impulses, so visibility can be expressed as formula (4).
When optical fiber be not subject to reversing and impressed field effect time, the Energy Coupling in tens meters between orthogonal mode is very little, almost can ignore, so can think p
1x≈ p
2x.As can be seen here, the polarization state of reflected impulse can be ignored the impact of detectable signal, and the amplitude of the first reflected impulse and the second reflected impulse is the principal element affecting detectable signal.Although do not have specific requirement to the Amplitude Ration of pulse before and after detection dipulse in scheme, from the expression formula of visibility, when ignoring the slight gap of weak reflection grating reflectivity, when the Amplitude Ration of front and back pulse is 1:1, the visibility of scheme is the highest.
The high s/n ratio dipulse phase place optical time domain reflectometer of the weak reflection grating of described fusion, when sensor fibre is subject to vibrational perturbation along the line, its dorsad return signal spectrogram will disturbance point place produce peak value.Fig. 6 applies the spectrogram along the line of the sensor fibre that records under vibration.We adopt piezoelectric ceramics to be applied with two vibrations in 3.93km and 3.98km place and continuous print two grating spacings, and in first time measures, the vibration frequency of piezoelectric ceramics is set to 30Hz, the set of frequency of piezoelectric ceramics is 9kHz in measuring by second time.(d) in (b) in Fig. 6, Fig. 6 is respectively to the amplification of the topography in the dotted line frame in (c) in (a), Fig. 6 in Fig. 6, wherein (a) in Fig. 6, (b) in Fig. 6 are first time measurement results, and (d) in (c) in Fig. 6, Fig. 6 is second time measurement result.In (b) in (a) in Fig. 6, Fig. 6, display spectrogram has two peak values at 3.95km and 4km place respectively, the frequency of its correspondence is 30Hz, and also show spectrogram in (c) in Fig. 6, (d) in Fig. 6 and have two peak values respectively at 3.95km and 4km place, the frequency of its correspondence is 9kHz.Measurement result is consistent with Setup Experiments, and display the present invention achieves the vibration survey to lower frequency and ultra-high frequency preferably.In (b) in Fig. 6, display spectrum signal becomes very smooth from 3Hz, no longer affected by noise, so native system at least can respond the low-frequency vibration being low to moderate 3Hz.
The above is only some embodiments of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (5)
1. one kind merges the dipulse phase sensitive optical time domain reflectometer of weak reflection grating, it is characterized in that, comprise narrow linewidth laser, photomodulator, circulator, data collector, avalanche probe, sensor fibre, pulse signal generator and be arranged on the weak reflection grating array on sensor fibre; Wherein,
Narrow linewidth laser, for exporting continuous light to photomodulator;
Pulse signal generator, for controlling the data acquisition of photomodulator and synchronous data collection device;
Photomodulator, for being modulated into first port of detection pulse-pair output to circulator according to the control of pulse signal generator by continuous light;
Circulator, injects sensor fibre for detecting dipulse by its second port, obtains the second port that the back rayleigh scattering light signal comprising a series of interference pulse inputs to circulator, and export avalanche probe to by the 3rd port of circulator;
Avalanche probe, exports data collector to for converting the back rayleigh scattering light signal comprising a series of interference pulse to electric signal;
Data collector, for processing electric signal, obtains the disturbance information of sensor fibre.
2. a kind of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating according to claim 1, it is characterized in that, described weak reflection grating array is engraved on sensor fibre, weak reflection grating array is made up of the weak reflection grating that N number of reflectivity is equal, reflectivity is-55dB ~-30dB, interval between adjacent weak reflection grating is equal
wherein, L is sensor fibre total length, and Δ L is the distance interval between adjacent weak reflection grating,
represent and round downwards.
3. a kind of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating according to claim 1, it is characterized in that, described detection dipulse comprises two light pulses, is respectively prepulse and afterpulse; If the time interval of front and back pulse is τ,
the pulse width of prepulse and afterpulse is equal, pulse width
wherein, c is the light velocity in vacuum, n
ffor sensor fibre refractive index, Δ L is the distance interval between adjacent weak reflection grating.
4. a kind of dipulse phase sensitive optical time domain reflectometer merging weak reflection grating according to claim 1, it is characterized in that, described photomodulator can be electrooptic modulator or acousto-optic modulator.
5., based on a kind of method merging the measuring vibrations of the dipulse phase sensitive optical time domain reflectometer of weak reflection grating according to claim 1, it is characterized in that, comprise the following steps:
Step one, continuous light is modulated into detection dipulse, launches according to predetermined period and detect dipulse for M time in sensor fibre;
Step 2, detection dipulse produce return signal dorsad in the sensor fibre being carved with weak reflection grating array, and return signal is the back rayleigh scattering light signal comprising a series of interference pulse dorsad; M detection obtains M bar return signal curve dorsad;
Step 3, by M bar dorsad return signal curve arrange in chronological order, obtain the time dependent curve of power that on sensor fibre, every bit is corresponding, and the powertrace corresponding to every bit on sensor fibre carries out Fourier transform, obtain spectrogram, thus realize the location of vibration and the large-range measuring to vibration frequency.
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| CN110617874A (en) * | 2019-10-16 | 2019-12-27 | 南京理工大学 | phi-OTDR system based on double-pulse phase-shifting interference and phase demodulation method |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6285806B1 (en) * | 1998-05-31 | 2001-09-04 | The United States Of America As Represented By The Secretary Of The Navy | Coherent reflectometric fiber Bragg grating sensor array |
| CA2309192C (en) * | 1997-11-07 | 2004-06-15 | Cidra Corporation | Improved array topologies for implementing serial fiber bragg grating interferometer arrays |
| CN102901525A (en) * | 2012-10-15 | 2013-01-30 | 武汉理工大学 | Ultra-large capacity time division and wavelength division fiber grating sensing system and query method thereof |
| CN104990620A (en) * | 2015-07-03 | 2015-10-21 | 南京大学 | Fiber bragg grating array-based phase-sensitive optical time domain reflection device and method |
| CN105181111A (en) * | 2015-09-21 | 2015-12-23 | 电子科技大学 | Ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system |
-
2016
- 2016-01-21 CN CN201610039975.4A patent/CN105547460B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2309192C (en) * | 1997-11-07 | 2004-06-15 | Cidra Corporation | Improved array topologies for implementing serial fiber bragg grating interferometer arrays |
| US6285806B1 (en) * | 1998-05-31 | 2001-09-04 | The United States Of America As Represented By The Secretary Of The Navy | Coherent reflectometric fiber Bragg grating sensor array |
| CN102901525A (en) * | 2012-10-15 | 2013-01-30 | 武汉理工大学 | Ultra-large capacity time division and wavelength division fiber grating sensing system and query method thereof |
| CN104990620A (en) * | 2015-07-03 | 2015-10-21 | 南京大学 | Fiber bragg grating array-based phase-sensitive optical time domain reflection device and method |
| CN105181111A (en) * | 2015-09-21 | 2015-12-23 | 电子科技大学 | Ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system |
Non-Patent Citations (1)
| Title |
|---|
| XIANGCHUAN WANG，ET AL.: "SNR Enhanced Distributed Vibration Fiber Sensing System Employing Polarization OTDR and Ultraweak FBGs", 《IEEE PHOTONICS JOURNAL》 * |
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